As the geographical domain in which companies conduct business continues to expand, the traffic of multimedia teleconferencing overloads multimedia communication central nodes. In the current market, most multipoint multimedia calls are scheduled in advance through companies that own multipoint control units (MCUs). An MCU provides the capability for three or more terminals and gateways to participate in a multipoint conference. If a company owns more than one MCU, it has more flexibility in hosting multimedia conferences. However, each MCU must be operated independently from the other MCUs in setting up and controlling multimedia conferences. Additionally, the capacity of each MCU is limited to multimedia conferences controlled by the corresponding MCU. Because each MCU is a single entity that handles both the call signaling and the media processing of the conference, the resources of the multiple MCUs cannot be combined to promote more efficient scheduling.
As the business of multimedia conferences continues to expand, more and more standards have been written for multimedia conferences, such as H.320, H.321, H.324, and H. 323 SIP. Those standards handle the call signaling and call control differently, yet use the same multimedia data standards such as H.261, H.263, MPEG, G.711, and T.120. The increasing number of multimedia conferences and standards drive the need for an MCU technology that is able to operate efficiently in a site utilizing a plurality of MCUs, which may share resources in order to increase the amount of traffic via the site. Furthermore, there is a need for technology easily adaptable to varying standards and increasing capacity.
The ITU and the IETF have defined a decomposition architecture for a multimedia gateway, which comprises of a multimedia gateway control unit (MGC), a multimedia process unit (MG), and the intermediary communication protocol, Megaco/H.248. The MCU, as defined in the H.323 standard, comprises of a Multipoint Controller (MC) and a Multipoint Processor (MP). The MC is an H.323 entity on the network that provides the control of three or more terminals participating in a multipoint conference. The MC may also connect two terminals in a point-to-point conference, which may later develop into a multipoint conference. The MC provides capability negotiation with all terminals to achieve common levels of communications, and may also control conference resources. However, the MC does not perform mixing or switching of audio, video and data.
The Multipoint Processor (MP) is an H.323 entity on the network providing the centralized processing of audio, video, and/or data streams in a multipoint conference. The MP provides the mixing, switching, or other processing of media streams under the control of the MC. The MP may process a single media stream or multiple media streams depending on the type of conference supported. The ITU has not defined the communication protocol between those two units in H.323, or a Decomposition MCU (DMCU) for other standards then H.323. One difficulty in operating the DMCU with other standards, such as H.320, is that signaling, control and media are multiplexed.
The decomposition architecture offers better utilization of resources, for one MC can control plurality of MPs, and a conference can share resources in a plurality of units etc. Also, an operator can upgrade its site by adding the appropriate units MP or MC according to it's the operator's needs. Those units can be from different vendors. In case of new versions or new standards the operator can update only the relevant unit MP or MC.
The MC functionality can be part of a general Media Gateway Controller (MGC). The MC can be considered as an MGC. Therefore, it is evident that there is a need for a DMCU that can work with plurality of endpoints supporting different standards.